Fracturing is a process of injecting large volumes of fluid having a suitable fluid composition into a well at high pressures to crack rock formations and create fissures for increased production of oil and gas.
Examples of processes and compositions that have been used for fracturing are described in U.S. Pat. No. 6,599,863, filed on Aug. 20, 1999 (issued on Jul. 29, 2003), U.S. Pat. No. 4,843,118, filed on Jun. 19, 1987 (issued on Jun. 27, 1989), and U.S. Pat. No. 6,705,400 filed on Aug. 28, 2002 (issued on Mar. 16, 2004), the entire contents of which are incorporated herein by reference.
Fluid compositions including a borate that are free of zirconium have been used at temperatures less than 107° C. At higher temperatures, the viscosity of the fluid drops quickly and the fluid is not effective in fracturing the subterranean formation, in stabilizing the fractured structure, or both. Zirconium based fluid compositions have been used for fracturing subterranean formations. Typically these fluids are shear unstable, i.e., the increase in viscosity upon reduction of the shear rate (e.g., as the fluid leaves the borehole and flows into the subterranean structure) is relatively small. Attempts to provide a fluid composition that can be used for fracturing subterranean formations, stabilizing the fractured structure, or both at temperatures greater than about 107° C. (e.g., greater than about 110°, or greater than about 115° C.) have required combinations of zirconium containing compounds and other compounds that result in expensive compositions, the need to combine multiple additives packages, or both. There is continued need for improved fluid compositions for fracturing subterranean formations that are less costly, can be used at higher temperatures, have good shear stability, or any combination thereof.